In wireless radio systems, such as the third generation (3G) system, radio resource management (RRM) is responsible for utilisation of the air interface resources. RRM is used in order to guarantee the so-called Quality of Service (QoS), to maintain the planned coverage area and to offer high capacity to the users. RRM can be divided into different functionalities, such as hand-over control, power control, admission control, load control and packet scheduling functionalities. These functions are required to guarantee the Quality of Service and to optimise the system data throughput with a mix of different bit rates, services and quality requirements.
RRM algorithms can be based on the amount of hardware in the network or on the interference levels in the air interface. The case where the hardware limits the capacity before the air interface gets overloaded is called “hard blocking”. The case where the air interface load is estimated to be above the planned limit is called “soft blocking”. It has been shown that soft blocking based RRM is advantageous as it provides higher capacity than hard blocking based RRM. Therefore, the present invention is concerned with soft blocking based RRM.
In case of utilising soft blocking based RRM, the air interface load needs to be measured. The estimation of the uplink load of the air interface can be based on the wideband received power level or on throughput. The present invention is engaged with load estimation based on wideband received power.
The received power levels can be measured in the base station. Based on such measurements, the uplink load factor η can be obtained. The corresponding calculations are explained hereinafter with reference to FIG. 1.
FIG. 1 shows a base station BS including an antenna 1. For simplicity it is assumed here that one BS equals one cell. The concept can however be extended to cover the case where one BS has several cells. The base station BS receives via the antenna 1 an own-cell interference power Iown from all intra-cell users connected to the base station BS. Furthermore, the base station receives via the antenna 1 an other-cell interference power Ioth from all inter-cell users that are utilizing the same carrier frequency but are connected to other cells than this own cell.
Furthermore, the base station BS receives system noise with a system noise power PN via the antenna 1 as well as from its own system components, i.e. system noise is at least partly inherent in a base station BS.
The own-cell interference power Iown, the other-cell interference power Ioth, and the system noise power PN represent the received wideband interference power, called total received power. This can be expressed by the following equation:Itot=Iown+Ioth+PN
The total received power is measured continuously by means of a measurement circuit 3A. The system noise power PN can be measured by the base station by means of a measurement circuit 2. The system noise power PN is commonly estimated at night, when the load is assumed to be small. Thus, the own-cell interference power Iown and the other-cell interference power Ioth are small as well. This results inPN≈Itot
The thus estimated noise power PN is then used in an RRM controller 3 to perform RRM functionalities, such as load control and admission control.
Unfortunately, this method cannot cope with system noise differences between day and night. Furthermore, this prior art method does not allow to determine the other-to-own cell interference ratio i at all, namely the ratio of the other-all interference power Ioth to the own-all interference power Iown. Thus, rather conservative noise rise targets have to be used in load control. This degrades system-performance.